A sash window assembly having a pivotal sash window adapted for installation in a master frame is well-known. The master frame typically has opposed, vertically extending guide rails to enable vertical reciprocal sliding movement of the sash window in the master frame while cooperatively engaged with the guide rails. The sash window may have an upper sash window and a lower sash window. The sash window also has a top sash rail, a base and a pair of stiles cooperatively connected together at adjacent extremities thereof to form a sash frame.
Hardware is associated with the sash window assembly such as tilt-latches and a sash lock assembly. Tilt-latches are supported by the top sash rail and releasably engage the guide rails to allow the sash window to pivot from the master frame. The sash lock assembly provides a locking mechanism between the upper sash window and the lower sash window. The sash lock assembly typically has one component that is supported by the top sash rail of the lower sash window and another component that is supported by the base of the upper sash rail. The sash lock components cooperate to provide the locking mechanism wherein the lower sash window and the upper sash window are prevented from sliding within the master frame.
One problem associated with typical sash locks is their ability to be manipulated by an intruder from outside the sash window assembly. Sash locks generally include some type of rotatable actuator arm and cam. The actuator is rotatable from a locked to an unlocked position. With some sash locks, the actuator arm or cam may be manipulated from the outside by a skilled intruder using a thin knife, stiff wire, or other diabolical tool of intrusion. Accordingly, while the sash lock assemblies provide a number of advantageous features, they nevertheless have certain limitations. The present invention seeks to overcome certain of these limitations and other drawbacks of the prior art, and to provide new features not heretofore available.